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# Refraction and spearfishing watch

1. Hi I was wondering if anyone could help me with a question from a physics GCSE paper. The paper was: PiXL AQA style PH1H PPE Nov 2014.
Q2b
The picture below shows a fisherman about to attempt to spear a fish. Using the ideas from part (a -this was just about refraction) explain where he should aim if he is to hit the fish you might find it helpful to add rays to the diagram and draw on the true position of the fish. (3 marks)

The image above was the diagram.
I understand refraction and can draw on rays for when it passes through a perspex block. I'm just not sure how it works for this example.

Thanks!
2. (Original post by Kmich)

Hi I was wondering if anyone could help me with a question from a physics GCSE paper. The paper was: PiXL AQA style PH1H PPE Nov 2014.
Q2b
The picture below shows a fisherman about to attempt to spear a fish. Using the ideas from part (a -this was just about refraction) explain where he should aim if he is to hit the fish you might find it helpful to add rays to the diagram and draw on the true position of the fish. (3 marks)

The image above was the diagram.
I understand refraction and can draw on rays for when it passes through a perspex block. I'm just not sure how it works for this example.

Thanks!
well you want to sketch the ray going from the fish into the fisherman's eye using your knowledge of whether light is refracted at a greater or lesser angle to the normal when it goes from water into air.

you can then extend the ray from the fisherman's eye back into the water to show where the fish *appears* to be from the fisherman's position.

The actual spear will obviously not be refracted when it's stabbed into the water - he needs to thrust it in a straight line to where the fish is.
3. (Original post by Joinedup)
well you want to sketch the ray going from the fish into the fisherman's eye using your knowledge of whether light is refracted at a greater or lesser angle to the normal when it goes from water into air.

you can then extend the ray from the fisherman's eye back into the water to show where the fish *appears* to be from the fisherman's position.

The actual spear will obviously not be refracted when it's stabbed into the water - he needs to thrust it in a straight line to where the fish is.
Thanks, I understand now where I need to put the lines. I think the bit I'm confused with is where to put the virtual image of the fish. Is it suppose to be directly above the actual image of the fish? I googled it and one thing said in front of the actual image and another said above the actual image so now I'm confused.
Thanks so much for the help.
4. (Original post by Kmich)
Thanks, I understand now where I need to put the lines. I think the bit I'm confused with is where to put the virtual image of the fish. Is it suppose to be directly above the actual image of the fish? I googled it and one thing said in front of the actual image and another said above the actual image so now I'm confused.
Thanks so much for the help.
I suppose anywhere reasonable on the correct line will be accepted... the spear will presumably keep going until it hits the fish, the fisherman's problem is just getting the correct angle and not really how far away the fish actually is.

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